Electric terminal



Dec. 2, 1969 T. M. cAIRNs 3,482207 EEEEEEEEEEEEEE AL United StatesPatent O 3,482,207 ELECTRIC TERMINAI..

Thomas M. Cairns, Detroit, Mich., assignor to Ford Motor Company,Dearborn, Mich., a corporation of Delaware Filed Apr. 8, 1968, Ser. No.719,479 Int. Cl. H01r 13/24 U.S. Cl. 339-258 3 Claims ABSTRACT OF THEDISCLOSURE An electric terminal formed from a thin metal sheet has anannular body portion of a first outside diameter and an annulardepressed portion of a second outside diameter. The second diameter isless than the first diameter but more than the first diameter minus twothicknesses of the metal sheet utilized to form the terminal. A slitruns along the axial length of both portions of the terminal so that theterminal may fiare outwardly when coupled with a mating terminal.

BACKGROUND OF THE INVENTION A great variety of electric terminals areavailable in today's market for a wide variety of applications. When aplurality of such terminals of the female type are associated with aterminal block to form a connector, an important criteria which each ofsuch terminals must meet is that only a certain force must be requiredto insert a mating terminal theren. A further requirement is that whenmated, the terminals must have a prescribed area of electrical contacttherebetween to insure the electrical characterisics of the circuit pathformed through the mated terminals. Another requirement is that theterminals must cooperate as above described after repeated couplings anduncouplings thereof.

The electric terminal of this invention is one that fulfills all of theneeds set forth above. More particularly, the terminal provides aprescribed, available area of electrical contact when mated. Theinsertion pressure required for terminal mating does not exceed apredetermined level and is Constant after the terminal has been inserteda minimum distance. Also, the terminal can be repeatedly mated withoutadversely affecting the electrical characteristics of the connectionmade therewith.

SUMMARY OF THE INVENTION This invention relates to an electric terminaland, more particularly, to an electric terminal both wherein apredetermined contact area is guaranteed between itself and a matingterminal and wherein the mating force does not exceed a predeterminedlevel.

An electric terminal Constructed in accordance with the teachings ofthis invention is formed of a thin metal sheet and has an annular bodyportion of a first outside diameter. The terminal also has an annulardepressed portion having a uniform outside diameter over at least afixed length. The outside diameter of the annular depressed portion isless than the first diameter but more than the first diameter less twothicknesses of the metal sheet forming the terminal. A slit runs alongthe axial length of both the body portion and the depressed portion ofthe terminal.

The terminal so formed is a female terminal and the internal surfacearea of the annular depressed portion thereof provides the electricalcontact surface area for the terminal to be mated therewith. The contactsurface is of prescribed area to insure prescribed electricalcharacteristics for the electric connection formed by the terminal. Therequirement that the annular depressed portion of the terminal have anoutside diameter less than 3i,482,207 Patented Dec. 2, 1969 the outsidediameter of the body portion of the terminal but more than the outsidediameter of the body portion less two thicknesses of the metal formingthe terminal insures two Characteristics of the terminal. First, theforce required for mating the terminal is not extremely high andsecondly, suflicient gripping pressure is applied by the terminal toinsure retenton of the terminal mated therewith during utilization ofthe electrical connection.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a schematic drawing of thefemale terminal of this invention shown in conjunction with a matingterminal.

FIGURE 2 is a schematic drawing showing the terminal of this inventionin a mated position.

DESCRIPTION OF THE PREFERRED EMBODIMENT Construction In FIGURE 1 thereis seen a female terminal, generally designated by the numeral 10, and amale terminal, generally designated by the numeral 12. The femaleterminal 10 is formed in accordance with the teachings of thisinvention. The male terminal 12, of standard construction, has a roundednose 14 on the leading portion thereof and wire gripping elements 16 onthe rear portion thereof. The wire gripping elements 16 are folded overto connect the terminal 12 to bared wire when the wire is inserted in areceiving Opening 18 of the terminal. The male terminal may have arecess 20 about the circumference thereof for a purpose fully describedin my copending application Ser. No. 692,822, filed Dec. 22, 1967, andassigned to the same assignee as this application. The terminal 12 maybe formed of a thin, electrically conductive sheet material such as a.012 inch thick sheet of SAE CA260 brass.

The female terminal 10, as shown in FIGURE 1, is also manufactured froma thin, electrically conductive sheet material such as the mentionedbrass material. The female terminal 10 has wire gripping elements 22 onthe rear portion thereof for the purpose of engaging bared wire when thewire is inserted within a wire receiving opening 24 of the terminal 10.The terminal 10 may also have a recess 26 about the circumferencethereof for the purpose described in my mentioned copending application.

The female terminal of this invention is Constructed so as to receive amating terminal in such a manner that a guaranteed area of electricalcontact is formed between the two terminals. In order to accomplish thisfunction, the leading portion of the female terminal is of uniqueconstruction.

With specific reference to FIGURE 1, the leading portion of the femaleterminal 10 is of generally annular construction. As previouslymentioned the terminal is formed from a thin metal sheet of electricallyconductive material. The entry portion of the terminal is formed as abell-mouth 30. The terminal 10 also has a main body portion 32 which hasa predetermined outside diameter. A slot 34 is formed after the mainbody portion of the terminal for a purpose to be described subsequently.The slot 34 extends along the axis of the terminal for a small distanceand extends around the circumference of the terminal a distance of notmore than of arc. The slot 34 separates the elastic, leading portion ofthe terminal from the static, rear portion of the terminal.

An annular depressed portion 36 of the female terminal 10 is shownintermediate the main body portion 32 and the bell-mouth 30. Thedepresed portion 36 extends along the axial length of the terminal 10for a distance d and may be formed in the terminal by a rollingOperation. The diameter on the outside surface of the annular depressedportion 36 of the terminal is controlled so that it is less than thepredetermined outside diameter of the body portion 32 but more than thepredetermned outside diameter of the body portion less two metalthicknesses of the material utilized to form the terminal. Thecriticalness of this dimension will be explained in the Operationportion of this specification.

A slit 38 runs along the axial length of the leading portion of theterminal 10 from the bell-mouth 30 to the slot 34. Similarly, a slit 40extends from the slot 34 to the wire receiving opening 24 in the rearportion of the terminal 10. The slits 38 and 40 are formed as a resultof the rolling of the terminal and have as opposing surfaces thereof theopposite lateral edges of the metal blank utilized to form the terminal.

Operation The Operation of the electric terminal constructed inaccordance with the teachings of this invention will be described withreference to FIGURE 2 of the drawings. FIGURE 2 shows the femaleterminal of this invention in an assembled Condition With a suitablemating terminal.

In assembling the terminal, the nose 14 of the terminal 12 is broughtinto engagement with the bell-mouth 30 of the terminal 10 and pressureis applied to move the terminal 12 axially into the terminal 10. A fullyinserted condition is achieved when the nose 14 of the terminal 12proceeds significantly beyond the end of the annular depressed portion36 of the female terminal 10. During vuthe insertion of the terminal 12,the slit 38 opens up uniformly along its length.

As was previously described, the outside diameter of the depressedannular portion 36 of the female terminal 10 is less than thepredetermined, outside diameter of the main body portion 32 of theterminal. However, the outside diameter of the depressed portion is morethan the predetermined, outside diameter of the main body portion lesstwo thicknesses of the metal utilized to form the terminal. The diameterof the depressed portion 36 is so controlled to insure that the forcerequired to mate the terminals 10 and 12 does not exceed a predeterminedlimit. More particularly, depression of the annular portion 36significantly beyond that described, namely, two metal thicknesses,substantially increases the insertion pressure required to mate theterminal well above a normal insertion force range of 1 to 3 pounds offorce. This increased insertion force is the result of the increasedpressure applied to the contact surface area of the terminal 10 by theinterior surface area of the depressed portion 36 of the terminal 12.This increased pressure means that the terminals cannot be easilyuncoupled after they are once mated.

The length of the dimension d of the annular depressed portion 36 of thefemale terminal 10 controls the electrical contact area between theterminals 10 and 12. More particularly, as seen in FIGURE 2, theinternal surface area of the depressed portion 36 is in physicalengagement with a contact surface area 42 of the terminal 12 to providethe electrical junction area between the terminals. Once the terminal 12is inserted to a position where the nose 14 passes beyond the depressedportion 36, further insertion of the terminal 12 does not increase theamount of electrical junction area between the terminals nor does itincrease the insertion force. The controlled junction area thus permitsa predetermined electrical characteristic for the electrical junctionbetween the two terminals.

The axial slot 34 in female terminal 10 permits the leading portion ofthe terminal to be elastic and to open freely along the slit 38, theslit 38 Opening uniformly -from front to rear as the nose 14 of theterminal 12 proceeds into the terminal 10. The exact location of theslot 34 between the recess 26 and the depressed portion 36 controls themaximum amount of insertion force required to insert the terminal 12.More particularly, as the slot 34 is moved to the rear or left, asviewed in FIGURE 2, the amount of metal which must be separated as theterminal 12 is inserted is increased and, therefore, the insertion forceis increased. Therefore, the exact position of the slot 34 gives anaccurate control as to the amount of insertion force necessary to insertand mate the terminals.

As previously mentioned, the slot 34 allows the slit 38 along the lengthof the leading portion of the female terminal 10 to open uniformly uponinsertion of the terminal 12 therein. Such a uniform Opening of the slit38 permits uniform and accurate contacting of the internal surface areaof the depressed portion 36 of the terminal 10 and the contact surfacearea 42 of the terminal 12. The internal surface area of the depressedportion 36 of the terminal 10 and the contact surface area 42 of theterminal 12 form parallel contact surfaces and such uniformity incontact insures that the electrical junction formed between the twoterminals is of a prescribed quality.

In a typical construction of the terminal 12 utilizing .012 inch thickSAE CA260 brass sheet, the O.D. of the main body portion 32 was .150 to.146 inch and the O.D. of the depressed portion was .126 to .122 inch.The length d of the depressed portion was .120 inch and the slot 34 was.04 inch wide and the leading edge thereof was located .240 inch fromthe bell-mouth 30. This terminal construction had an average insertionforce for terminal mating of two pounds of force.

There has been disclosed herein a terminal of such construction that'nomore than a controlled, predetermined maximum insertion effort isrequired to insert a mating terminal therewithin. The terminal is alsoof such construction that a uniform quality junction is consistentlyformed between mated terminals. Further, the construction is relativelyinexpensive to manufacture and of Superior value in forming electricalconnectors.

The invention disclosed iwill have many modifications which will beapparent to those skilled in the art in view of the teachings of thisspecification.

What is claimed is:

1. In an electric terminal formed from a thin metal sheet: asubstantially annular body portion of a first outside diameter; anannular depressed portion coaxial with said body portion, said annulardepressed portion having a uniform outside diameter over at least afixed length which diameter is less than said first diameter but morethan said first diameter less two thicknesses of the metal sheet formingthe terminal; and a slit running along the length of both said bodyportion and said annular portion.

2. In an annular, electric terminal formed from a thin metal sheet: anentry portion; a body portion of a first outside diameter; a depressedportion interconnecting said body and entry portions, lsaid depressedportion having a uniform outside diameter over at least a fixed lengthwhich diameter is less than said first diameter but more than said firstdiameter minus two thicknesses of the metal sheet forming the terminal;and a slit running the axial length of at least said body portion andsaid depressed portion of said terminal.

3. The electric terminal as defined in claim 2 further including a slotin said body portion of said terminal, said slot both extending acrossand along the axis of said body portion and intersecting said slit.

References Cited UNITED STATES PATENTS 2,269,605 l/l942 Smith. 2,8l0,89310/1957 Nijand 339-9 FOREIGN PATENTS 992,456 7/ 1951 France.

MARVIN A. CHAMPION, Primary Examiner JOSEPH H. MCGLYNN, AssistantExaminer

